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Monday, April 30, 2012

Organic food and agricultural romanticism

A seed has three main parts: an outer husk to protect it until germination (bran), a reserve of energy (endosperm) and the cells that have the DNA to kick start growth (germ). After planting into the earth with sufficient moisture to break down the bran, the process of growth starts. The germ cells use the nutrient reserve in the endosperm to get started in making fledgling leaves and roots and eventually, the seedling breaks through to the infinite energy of photosynthesis from sunlight. The roots develop and start to move water from the soil through the plant to be evaporated from the leaves and in so doing, the water brings the minerals the plant needs to grow, of which one is nitrogen.

Nitrogen is absorbed from the soil as either ammonium (NH4+) or as nitrate (NO2-). Both are released from commercial fertilizers and both are released from farmyard manure. The ammonium and the nitrate ions of both commercial fertilizers and manure are absolutely identical and there is simply no way a plant can differentiate between the two. The same is true of all the other minerals which plants absorb from soil such as sulphates and phosphates. The minerals absorbed are used for all sorts of functions but most of the nitrogen and sulphur ends up in plant amino acids and proteins. Some will end up in the vitamins that the plant makes and also the phytochemicals which give plants their colour, texture, smell, taste and so forth. The plant assemble all of these compounds according to its DNA. Unlike animals, plants do not have any nervous system and thus cannot make choices. Thus they are hardwired to do exactly what their genes tell them to do. Thus a carrot seed becomes a carrot and not a parsnip and vice-versa. Those who espouse organic farming harbour the view that the plant grows differently in the presence of organically derived minerals as compared to those that are industrially derived. This is utter nonsense. Michael Pollan, for example, argues that synthetic fertilizers force plants to grow at a faster than average rate and that in so doing, the plants get things wrong. Rubbish!!!

Plant growth, like animal growth, is determined by growth hormones which are genetically controlled but which also respond to climate. These hormones determine the rate of growth and thus the demand for minerals from soil and it doesn’t matter one iota if the minerals are from manure or “chemical” fertilizers. This has an analogy in human growth. Athletes can eat as much protein as they like but that will not drive muscle growth. Hormones drive muscle growth and athletes can take hormones illegally or they can increase their natural levels by training and conditioning.

Let us now turn to the idea promoted by organic enthusiasts that organic food is tastier and more nutritious. Firstly, theory would say that that is not possible as explained above but the proof of the pudding is in the eating. Research published in the American Journal of Clinical Nutrition and FUNDED by the Danish organic farming movement, categorically failed to find any difference in the nutritional value of plants grown under organic or conventional farming conditions. Equally, researchers at the University of Kansas found that consumer panels could not distinguish between the taste of organically grown fruit and vegetables and those grown using industrially produced fertilizers. Endless reviews by eminent scientists and funded by governmental bodies reach similar conclusions. For example, the UK Food Standards Agency commissioned a review of all the literature relating to the nutritional quality of organic food. The review concluded: ‘On the basis of a systematic review of studies of satisfactory quality, there is no evidence of a difference in nutrient quality between organic and conventionally produced foodstuffs’. The taste and flavour of plants are determined to some extent by microclimate and the variation in these qualities between growing seasons or between different parts of the same field exceeds any variation between crops grown under either conditions.

The organic movement also suggest that foods grown under organic conditions are better for the environment. A report commissioned by the UK Department of Food, Environment and Rural Affairs

concluded: “There is insufficient evidence available to state that organic agriculture overall would have less of an environmental impact than conventional agriculture. In particular, from the data we have identified, organic agriculture poses its own environmental problems in the production of some foods, either in terms of nutrient release to water or in terms of climate-change burdens. There is no clear-cut answer to the question: which ‘trolley’ has a lower environmental impact - the organic one or the conventional one?”.

Finally, we turn to pesticide residues. By definition, organic food should not contain residues of synthetic pesticides. However, studies repeatedly show that about 15% of organic crops will contain some minute level of pesticide residues which is explained by “drift” ~ farmers upstream from the wind direction spraying their crops with downward drift of some spray. By definition, conventional crops will contain pesticide residues and as with organic crops, the levels are minute. In neither case do these residues contain a shred of threat to health since they are present at ultra-low levels, and well below the agreed residue levels in legislation. Of course there have been cases of neglect or accident where pesticide levels above this threshold have been found and even some very rare cases of sickness arising from these high levels. But these are accidents or neglect and they can also occur in organic agriculture where contamination with E. Coli on organic food has led to food poisoning.

As I pointed out in a previous blog, all the scientific arguments in the world will not change the views of the agricultural romanticists. Theirs is a view based on emotion and not science, or a distorted view of science. But if such arguments help the very many who haven’t the resources to pay for organic food to feel better about conventionally produced foods, then it is very worthwhile making the case.

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"Ever seen a fat fox ~ Human obesity explored"

About Me

I graduated from University College Dublin in 1971 with an Masters in Agricultural Chemistry, took a PhD at Sydney University in 1976 and joined the University of Southampton Medical School as a lecturer in human nutrition in 1977. In 1984 I returned to Ireland to take up a post at the Department of Clinical Medicine Trinity College Dublin and was appointed as professor of human nutrition. In 2006 I left Trinity and moved to University College Dublin as Director of the UCD Institute of Food and Health. I am a former President of the Nutrition Society and I've served on several EU and UN committees on nutrition and Health. I have published over 350+ peer reviewed scientific papers in Public Health Nutrition and Molecular Nutrition and am principal investigator on several national and EU projects (www.ucd.ie/jingo; www.food4me.org). My popular books are "Something to chew on ~ challenging controversies in human nutrition" and "Ever seen a fat fox: human obesity explored"